Having been among the batting leaders for several months (before tailing off to finish at .298), Ronning was promoted to the Montreal Royals of the International League for 1952. But he struggled to hit in the higher classifications. Ronning blamed this on a severe virus he contracted while playing for the Fort Worth Cats in the Texas League in 1953, which dropped his weight from 215 lbs to 160 lbs; however, the .650 OPS he posted in 1953 was the highest OPS of his seven seasons (1952-1958) in AA and AAA ball.

Ronning was a player coach for the Montreal Royals in 1957, and briefly managed the club for a few days in June, as Tommy Holmes took over for Al Campanis. After posting only a .494 OPS for the Spokane Indians of the Pacific Coast League in 1958, Ronning dropped down to the lower classifications, and began a career as a manager.

After the 1968 season, Ronning joined the expansionMontreal Expos as a scout. He remained with the organization through 1974, and then scouted for the Major League Scouting Bureau from 1975-2002. He was named the West Coast Scout of the Year in 2002. [2] He signed, among others, Jerry White, who spent 10 years with the Expos.